Why studying will never help you speak a language like a child?
You can never speak a language by just studying it, no matter how much you study. A language is a means of communication. We have endless ways of saying what we want to say in our mother tongue. Language gives us the freedom to say what we want to say. Unfortunately, many times when we are taught a second language, (and many times also when we learn it ourselves) we are taught in ways that serve to effectively limit our possibilities and what we can say. When you study, you acquire vocabulary, you improve your grammar and you do exercises. If you goal is to just pass English exams like TOEIC, TOEFL or IELTS, use memorization techniques and prepare for these exams. However, if you want to become fluent in English and speak with a clear accent with confidence, the best thing to do is to talk with a native speaker. Stop looking at conversations with human beings as a test that you have to pass.
Average child needs at least a few years of his life to start producing any complex sentences. They have nothing but time. They just sit and listen. And they spend almost all of that time learning a language in one way or another. That’s their only entertainment. From birth it takes you years to be able to confidently distinguish between all sounds in your native language. Adults are further advanced when it comes to cognitive development. What’s more, they have already acquired their first language. It gives them the advantage of having the pre-existing knowledge! No need to learn how to distinguish m from n. No need to learn the vast majority of sounds that are the same between those languages. No need to develop the muscles in your voice box and tongue so you can simply attempt to make noises with them. So you can focus on the language, right? Of course there are reasons that children are better learners. There always will be. Children have a smaller vocabulary and it is easy to learn enough of a second language to communicate their needs. Adults have a much larger vocabulary and think and communicate in more complex ways than children. This means it takes them longer to acquire the ability to communicate effectively in a second language.
How to Naturally Learn a Language Like a Child
So, if studying isn't how you learn to speak a language, then what is? If you want to learn a language like a child it’s important to focus on what’s relevant. As a foreign language learner, you need to devote time to actively listen to your target language. Take every opportunity to listen to the language as spoken by native speakers. Listen for the inflections, tones and rhythms of words.
Children spend a lot of time learning their first language. So copy their enthusiasm, their joy of learning and their willingness to make mistakes and not care about them. The best approach means nothing if you don’t use it. Adults have such a big advantage in that they can do things kids can't. They can arrange to meet up with people to practice the language.